taccone



Nov. 13, 1962 Filed May 9, 1960 FIG.'1

R. W. TACCONE MOLD FOR CASTING 2 Sheets-Sheet 1 FIG. 7

Nov. 13, 1962 R. w. TACCONE MOLD FOR CASTING 2 Sheets-Sheet 2 Filed May9, 1960 INVENTOR.

(MM/ firm Filed May 9, 1960, Ser. No. 27,847 3 Claims. (Cl. 22-42) Thisinvention relates to molding machines and, more particularly, tomachines for making sand molds for eastings.

It has been ascertained that molds for castings are difficult to handledue to the fact that, on leaving the molding machine, they have to beplaced on pattern plates in order to avoid the subsidence of the mass ofsand under the effect of shocks, vibrations, the pressure of the gas atthe moment of pouring the molten metal, the weight of the cast metal,etc.

It has even been noticed that it is necessary to weigh down the moldsfrom the top of the mass of sand itself. The action of the weights whichare put on the mass of sand to weigh the molds tends still more todeform the mold and, consequently, makes the pattern plate even moreindispensable.

To avoid all these inconveniences, the inventor has had the idea ofgiving to the opposite surface of the mass of sand, to that in which theimpressions are formed, the form of an arch. In this way, the verticalpressure is converted into horizontal or diagonal thrust and any pointalong the surface of the arch offers approximately the same resistance.

After numerous long and diflicult experiments in choosing the suitablecomposition of the sand, its degree of humidity, the way of compressingit, the distribution of pressure on the surface of the sand, the way ofexerting this pressure, and the relation between the height of the moldand the area of its surface, the inventor has constructed the moldshaving, on one face, the impressions and, on the other face, at leastone arch capable of offering high resistance to pressures and made sothat, as far as possible, any point along the surface of the arch offersapproximately the same resistance.

For a given mold box, the ratio between the height of the mold and thearea of the surface of the sand can be varied by positioning cross barson the inside of the mold box in order to make several arches, ifnecessary.

The invention thus has as its object the provision of a new industrialproduct constituted by a mold for casting comprising, in combination, amold box formed simply by an open frame for the wall of the mold and bya mass of molding sand packed in the interior of this mold box andhaving, on one of the open faces of the said box, at least oneimpression intended for receiving the molten metal and, on the otherface which is also open, at least one arch capable of offering a highmechanical resistance to forces transmitted from the interior of themold toward this face.

According to the invention, it is particularly intended that use shouldbe made, in order to obtain molds with open faces according to theinvention, of machines comprising flexible diaphragms of a large surfacearea arranged in such a Way as to permit the desired distribution ofpressures on the surface of the mass of sand and the obtaining of therequired gradients of pressure in the said mass necessary to assure theformation of resistant arches according to the invention.

nited States Patent ice used, it is intended to include any moldingagent which is suitable for making a mold.

It can be assumed that the very flexible, non-elastic diaphragm assuresa pressure which is uniform over the whole of the surface of the archand a slightly higher pressure than in the interior of the mass of sanddue to the fact that this diaphragm does not exert any mechanicalresistance at any point on its surface. This phenomenon can be comparedto the construction of a pre-stressed beam. The diaphragm is only thereto form a separation between the fluid (compressed air) exerting apressure against one of its faces and the mass of sand against which thediaphragm is freely pressed.

When the mold is being made and when the compressed air is forcedagainst the upper face of the diaphragm to pack down the mass of sandcontained in the mold box, the sand tends to be a little less compressedin the zone which is close to the outside edge of the mold box than inthe other zone. This is why, according to a particular embodiment of theinvention, the compressed air is made to strike the interior rim of themold box and not the complete surface in such a way that the peripheralzone of the mass of sand is the first to be submitted to the directpressure of the compressed air, through the intermediary of thediaphragm, in order to compensate for the tendency that the sand has tobe less compressed around the outside edge of the mold box.

According t the invention, the diaphragm is held by the lower edge of apart in the form of a head under which one brings the mold box in orderto compress the mass of sand. In the interior of the head is alsoprovided a deflector constituted by a horizontal plate which almostcompletely seals the head, except on its inside rim, where it is open,to allow the compressed air to pass.

The invention will be better understood by reading of the followingdescription and by examination of the accompanying drawings which show,by way of non-limit- This construction makes it unnecessary to submitthe mass of sand or other material utilized to any treatment intended tomodify the composition of the mixture in order to augment itsresistance.

It should be understood that when the word sand is ing examples, severalembodiments of the invention.

In the drawings:

FIG. 1 is a vertical sectional view through the middle of a moldaccording to the invention and of a device for packing the mass of sandin the mold box;

FIG. 2 is, to a smaller scale, a plan view of the deflector platemounted in the device;

FIG. 3 is a plan view of a variation of the mold;

FIG. 4 is a sectional view taken on line IV-IV of FIG. 3;

FIG. 5 is a plan view of another variation of the mold;

FIG. 6 is a sectional view taken on line VI-VI of FIG. 5;

FIG. 7 is a section of a mold for casting according to the inventioncomprising a mold box which is open on the top and the bottom; and

FIG. 8 is a cross sectional view of flask in assembled relation.

The mold according to the invention represented in FIG. 7 is formed, incombination, by a box 1 and a mass of sand 2 packed in the interior ofthe box 1. The box 1 is constituted simply by a frame which forms thewall of the mold and which is completely open toward the top and thebottom.

The mass of sand 2 has an impression 3 on the side of the bottom openface of the box 1 for receiving the molten metal. The impression 3 isformed by means of a pattern. The sand 2 also has an arch 5 on the sideof the upper open face of the box 1 which is calculated to offer a highmechanical resistance to the forces transmitted from the interior of themold toward this face, particularly under the effect of shocks,vibrations, and the pressure of the gases at the moment of pouring themolten metal as well as the Weight and pressure of the cast metal.

two parts of the To make the mold, the box 1 has, for example, beenplaced on a pattern plate 7 on which a pattern 4 is positioned as shownin FIG. 1, a convenient quantity of molding sand or any other suitablematerial has been deposited, and the sand has been packed down by meansof a device comprising a head 8. The lower edge of the head 8 has thesame contour as that of the box 1 and the edge of a flexible,non-elastic diaphragm 9 is attached thereto. The diaphragm 9 has asurface area easily large enough for being spread out against the top ofthe mass of sand, without ever being stretched. The edge of thediaphragm 9 is held between the edge of the head 8 and a clamping ring11, of the same contour as that of the head 8 and of the mold box 1, andis fixed to the head 8 by screw bolts 12.

The clamping ring 11 extends inwardly all around the flask and forms ashelf for supporting the edge of the diaphragm 9 and a deflector forair. The inner edge of the diaphragm 9 is rounded to protect thediaphragm 9.

The top of the head 8 has perforations 13 through which compressed airis admitted to etfect the packing down of the sand. In order that thedirect pressure of the compressed air is first made to act near the wallof the box, the interior of the head is fitted with a horizontaldeflector plate 14, the outside edge of which has notches 15 cut out ofit to a distance of no more than twice the inward extent of the clampingring 11. The plate 14 is welded to the inside wall of the head 8 byparts 16 formed between each successive notch. The compressed air whichis admitted into the head by the perforations 13 to effect the packingdown of the sand passes afterwards through the notches 15 in thedeflector plate 14 and then strikes against the diaphragm 9 in thevicinity of its outside edge.

To make the mold, a convenient composition of sand or other equivalentmaterial is chosen, with the correct degree of humidity. The desiredamount of sand is then placed in the box which is positioned under thehead, which has the diaphragm 9 attached to it, and compressed air isthen admitted into the head. Due to the previously mentioned propertiesof the diaphragm 9, the air exerts an evenly distributed pressure on themass of sand and forms, on the top surface, an arch, any point along thesurface of which offers approximately an equal resistance to pressure,the mass of sand on the interior being submitted to a corresponding andequally uniform compressron.

The relation between the height of the mold and the area of its surfaceis chosen in such a way that a sufficient thickness of sand remainsbetween the impression of the pattern and the crown of the arch.

In FIGS. 3 and 4, a variation of the mold is represented in which thebox 1 is fitted, on the inside, with cross bars 18 on which thediaphragm for packing down the sand rests, in such a way as to formseveral arches such as indicated at The choice of the number and of theform of the arches depends upon the form of the impressions and of theirdimensions, as well as the form and the dimensions of the mold box andit is determined in such a way that a mold is obtained having all therequired qualities of resistance to pressure.

Thus, for the form of the mold represented in FIGS. 5 and 6 whichutilizes a circular mold box, cross bars are provided in the form ofcantilevered radial ribs 21 of curvilinear profile which are supportedat their roots by the inside wall of the box. The cross bars 18 of theembodiment in FIGS. 3 and 4 are supported at their two extremities bytwo inside opposite faces of the box.

It will be understood that the invention is in no way limited t theembodiments described and shown in the drawings and many modificationsand changes may be made therein by those skilled in the art, accordingto the desired applications, without departing from the scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A molding machine comprising a flask frame open at the top and bottomand supported on said molding machine, a flexible diaphragm supported onsaid molding machine over said flask frame, and means to direct air athigh pressure onto said diaphragm at spaced positions disposed at theouter edges of said flask frame only whereby said diaphragm compressessand near the edges thereof more than at the center, thereby forming thesurface in the shape of an arch.

2. The machine recited in claim 1 wherein said means to direct air ontosaid diaphragm comprises a plate supported over said frame, and aclamping ring attached to said plate and surrounding the edges of saidframe and underlying the edges of said diaphragm whereby said airimpinging on said diaphragm is directed away from the edges of saidframe.

3. The machine recited in claim 2 wherein said plate has openings aroundthe edges thereof and overlying said clamping ring.

References Cited in the file of this patent UNITED STATES PATENTS989,578 Deville Apr. 18, 1911 1,671,589 Kahler May 29, 1928 1,883,542Campbell Oct. 18, 1932 2,843,893 Davis July 22, 1958 2,854,712 DietertOct. 7, 1958 2,857,636 Whitesell Oct. 28, 1958 2,859,499 Floehr Nov. 11,1958 2,864,136 Taccone Dec. 16, 1958 2,968,846 Miller Jan. 24, 1961FOREIGN PATENTS 17,511 Great Britain 1899

